Compound expanding underreamer



May 5, 1931. J, GRANT 1,803,669

COMPOUND EXPANDING UNDERREAMER Filed Deo. 21, 1927 4 Sheets-Sheet l May 5, 1931 J. GRANT coMPoUND EXPANDING UNDERMAMER Fi`led Dec. 2l. 1927 4 Sheets-Sheet May 5, 1931. 1 GRANT v 1,803,669

May 5, 1931. J. GRANT 1,803,669

` COMPOUND EXPANDING UNDERREAMER l Filed Deo. 21. 1927 4 Shen-:'cs-Sheet 4 Zag/6 zag 7.

Patented May 5, 1931 JOI-1N GRANT, OF LOS NGELES, GALFORNIAv COMPOUND EXPANDNG NDERREAMER Y Application filed Becember 21,1927. Serial No. 241,653.

5 form of reamer hereinafter described is deprovide a reainer which has a comparatively large expansion. Structural limitations and factors ofdesign put a limitation upon the amount of expansion that may be obtained in a givenreamer structure; and, particularly in reainers used for rotary.,work,v

this limitation has been such as to malte it difficult to obtain the amount of expansion necessary to underreamlarge enough to pass a pipe with a tool that Ywill pass through the pipe when contracted. rlhe present practical aspect' of my invention is directed to the production of a rotary underrcamer that can be passed through a pipe and that will have sufficient expansion below the pipe -to ream a hole sufficiently large to allow the pipe to pass freely through it-in other words, a hole substantially larger than the outside of the pipe and its collar.

l accomplish my object by providing a reamer which has two distinct operations of expansion, so cooperating as to givefto the r' cutters an expansion which is the accumulation or addition of tivo elements of eXpansion. Thus, in the present typical and illus# trative design l provide one-element of eX- pansion which is .operative by a movement of the cutter with relation to the mandrelon which it is mounted; and another movement of efipansion is provided by a movement of the mandrel itself7 carrying the cutter with it. This general principle of operation, including independent-movement of the cutter with relation to its. supporting mandrel, ,and also Vmovement of the mandrel and cutterv together, isY applicable to many different forms and designs of expanding.

reamers. But `for the purpose of V illustrartive description of the invention, I have chosenhere to describe the'application of 4the present invention to a form vof reamer generally similar to thatshown in my application `slerial No. 225,270', filed October 10, 1927, entitled Expanding roller underreamer. In that type'of underreamer, the cutter carrying mandrels, of which, in praotice, there are more than one, are eccentri- 'cally spaced from the center of the tool body, and roller cutters surround the mandrels and are movable longitudinally thereon, the 'mandrels and cutters being so formed y that longitudinal movement causes projcction or expansion of the cutters. Specifically speaking, the'application of my present invention toy that particular type of eXpan-v sive reamer .consists primarily in giving the mandrelsthemselves a lateral movement, and preferably a lateral movement of rota-,` tion about longitudinal` axes. The invention itself, as well as the selected specific adaptation of it, will now be best understood from the following detailed description, refer'ence being had to the accompanyingdrawings,l in which Y Fig. lis an elevation of said reanier; Fig. 2 is an enlarged central longitudinal section of portions. of the reamer,both Figs.

1v and 2 showing the tool in contracted position. 'Figs 8', 4,'.5 and-6 are cross sections taken on lines 3--3, 5-5 and (i4-(lof Figs. 1 and`2. n

Fig. 7 is a view similar to Fig. 2, showing the reamer expanded;

Figs. 8, 9 and lOare sections on lines 8--8,

.Q -9, 10-10, respectively, of Fig. 7,;

Fig. 11 is a bottom end view of the reamer body; Y V

Fig. 12 is a plan view ofthe bearing ring,

hereinafter described, and located between the reamer bodyand the sub which extends below the reamer body; j

Fig. 13 is a section on line 13-13 of Fig.

Figs 14E and 15 are diagrammatic views illustrating the expanding and collapsing movements of a mandrel and cutter;

Fig. 16 is a side elevation of a modified form;

are'

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Fig. 17 is a central longitudinal section of the modified form; and

Fig. 18 is a plan of the bearing ring which is located at the lower' end of the reamer body in the form ot Figs. 16 and 17.

In the drawing` a suitable body is shown at 10 provided with the usuall threaded pin 11 at its upper end for connection with a rotary drill stem. 1n the particular design here shown illustrate a reamer having three cutters; the body is accordingly provided with three longitudinally extending slots 12, the particular configuration of which will be hereinafter explained. At the lower end oi the body a sub 13 is screwed onto the body, and a bearing ring held in place as illustrated between the body and the sub. This bearing ring, which is nonrotatable with reference to the body and is put in place without the necessity of rotating with reference to the body, forms the bearing element for the lower ends of the cutter supporting mandrels 15, the upper ends of these mandrels eing journalled in bores 16 in the upper part of the body above the upper ends of slots 12. Reaching up from the lower end of the body is a cylindric bore 17, the upper end of this bore being above the lower ends of slots 12, so that the lower ends of the slots open into the bore. Propeller actuating sleeve 18 is slidable and rotatable in bore 17 and carries the critter propeller 19 at its upper end and has a head 2O at its lower end. This head 20, in the uppermost position of sleeve 18, may bear up against the lower end of the screwthreaded pin 10a of the body, the head and sleeve being adapted to move vertically between the positions shown in Figs. 2 and 7, and being pushed up by the action of a spring 21, the lower end oit which rests upon a collar 22, the collar in turn resting upon the screw-threaded pin 23 of drilling bit 24 which is attached to the lower end of sub 13. Spring seat collar 22, as shown most clearly in Fig. 13, is provided with peripheral notches or grooves 25, and the bore of sub 13 has lugs or other suitable projections 26, which enter these grooves to prevent relative rotation of spring seat collar 22. Spring 21 acts both as a compression and torsion spring; and when the tool is assembled and the spring seat collar 22 is put in place, it is turned to put the spring under torsional strain, so that the spring is at all times acting` to turn sleeve 18 and propeller 19 in a left-handed direction, looking down upon the parts. In order that the spring may` have this torsional action, its ends are rotativcly connected to head 2O and collar 22, by having its ends, as indicated at 27, set in openings in the head 2O and collar 22, respectively.

lllandrels 15 have at their ends the upper eccentric bearing pins 35 and the lower eccentric bearing pins 36, the lower pins being journalled in bores 37 in bearing collar 14. The eccentric axes of bearing pins 35 and 3G are coincidental; and in tne diagrammatic Figures 14 and 15 the centers ot these bearing pins are designated C. linmediately adjacent the bearin pins each mandrel has a head 38 in the form of a crank; and to facilitate assembly the lower crank head 38 is made removable from mandrel 15. Each mandrel 15 is provided with two fully .cylind 1ic parts 40 and with. two reduced 'parte 41, one of the reduced parts 41 being located between the fully cylindrie parts 40 and the other reduced part 41 being located below the lower cylindric part 40; so that the mandrel is made up of two spaced fully cylindric parts 40 and two spaced reduced parts 41. The cutter, which is here illustrated as a rotating roller cutter 42, has at or near its ends two cylindric bores 43 of proper sine and or" proper longitudinal spacto have a rotating bearizig upon mandrel rts 40 when the cutter is in the position shown in Fig. 7. Intermediate the two bearing b s 43 the critter has an internal bore 'eenling-..-ent as shown at 44, which enlargement iits over the lower mandrel part 40 when the cutters are in the collapsed position shown in Fig. 2, allowing the parts of the cutter at the smaller bores 43 to move back aga`nst the mandrel reduced portions 41. 'llhis particular intertormation ot' mandrel and cutter causes or allows contractive and exoansive movements oi' the cutter due ative movement between the cutter and mandrel, specifically due to relative longitudinal movement between the cutter and mandrel; and such intertormation, as se far described, is generally similar to that set forth in my (3o-pending application Serial Number 225,270, tiled (letober 10, 1927, also in my co-pending application Serial Number 122,340, tiled July 14, 1926, entitled Expanding roller underreamer; and will need no further particular explanation here ef;- cept for its particular adaptation to the specific forni or" double expanding arrangement here described.

By reference particularly to 14 and 15 it will be seen that the center C1 of the full mandrel parts 40 is eccentrically ollset from center C about which the mandrel rotates. It will also be seen that center C2 (the center of roller 42 when collapsed) as most plainly shown in Fig. 14, is offset from center C1 in an ina/'ard direction toward the center of the whole tool.l when the parte are in their collapsed position as shown in Figs. 2 and 14. The reduced portions 41 of the mandrel are conveniently made by cutting into the outer surface of the mandrel (the surface which is outermost in the collapsed position of Fig. 14), and this cutting is done on center C2; so that the outer surfaces of .portions of the mandrel, but are merely offset inwardly. Thus` when the cutter is in the collapsed position shown in Figs. 2 andY 14 its bores 443 engage the-.thenrouter face of reduced portions 41 and have a good flat bearing' on those portions, obviating any liability ofthe bearing surfaces of the roller being scored or mutilated. V

The action of expansion in this device involves two different movements-of the roller cutter. vThese movements take place more or less simultaneously, but for clarity of description they may be'described successively, Thus one movement of expansion involves the movement of roller 42 upwardly from the position shown in Fig. 2 to the relative position shown in Fig. Y. With the mandrel in the position shown in Fig. 14 and the roller in the lower position shown in Fig. 2, the roller lies inwardly towardrthe center of the tool; because in that position of the mandrel, the reduced mandrel portions 4l are, as explained before, oifset inwardly toward the center of the whole tool.v Consequently an upward movement of the cutter to the position of Fig. 7 Vforces thel cutter outwardly by the linear distance represented bythe offset of reducedV portions 41the linear distance Vbetween ,centers C1 and C2. To facilitate outward movement of the cuttern upon upward movement. the' lower ends of the full mandrel portions 40Vare beveled indicated at 40a.

lVith the cutter in full bearing upon the full cylindric mandrel portions 40, thena swinging of thema-ndrely from the position of Fig. 14 tothe positionof Fig'. 15 causes further expansion of the cutter to the fully"'ex panded position, due to the relative eccentric vdisplacement of centers C and C1. Thus the full vand final expansion of the cutter is dueto the two movements, one a movement of the cutter relative to the mandrel, the other a movement of the mandrel relative to the.

body; and the cutter-reaches its and fully expanded position as shown in Figs. 7, 8, 9, 10 and 15. ln this fully expanded position of the cutter-the center C1 is lo' Vleft-handed direction on their centers C.

But that, tion in which the mandrels have been swung on their centers Vfor expansive movement of `the' cutters; `and means are provided, here- `peller tube.

it will be noted, 4is the same direc-` inafter explainedin detail, not only to stop further swinging of the mandrels in that direction but also to give the cutters direct thrust'bearings-upon the tool body so as to take Itorsional and iii-thrust strains off the mandrels 'and their bearings.- These inatters, however, I will explain in detail after explaining the means by which the cutters are moved relatively to the mandrels and the mandrels are rotated.` g

Propeller 19, which I have before referred to, is mounted upon the `ripper end of propeller tube 18, and is mounted in suchmaiinerV as to be rotatively fast upon the pro- For instance, as most clearly shown in Fig. 6, the tube and propeller may interengage with splines 19a. The tendency of spring 21 is at all times to movethe propeller upwardly Vand to swing it around in a left-handed direction, looking down upon it. The propeller has slotted arms 19?) which engage the lower parts of mandrels 15' directly under the lower ends of cutters 42. ln the lowermost position of the `propeller, with the cutters contracted, the pro.-

peller lies in `the position best shown in Fig. 6, and in this position the mandrels are swung to the collapsed position diagraminatically shown in Figs. 14 and 6. VAlso :in this position it will be noted, by particular referenceV to Figs. 1 and 6, that the arms of.

the propellers are prevented from rotating left-handedly by reason of the propeller arms resting.V against a `wall surfacel 12a of the bodyslot 12. in thisposition of the propeller the cutters arey consequently in their'lowerlpositions as shownV in Fig. 2 and the Vmandrels are in their innermost positions of rotation, as shown in Figs. 6 and 14.

As the propeller moves up it moves the cuti ters upwardly on theV mandrels, the cutters resting at their lower ends directly on the propeller.

have -moved upwardly to a point above'the no As soon as the propeller arms slotted wall surface 12a, theyV can then begin to rotate toward the'left,l as-they move upwardly, because of the inclined slotted wall surface shown in Fig. 1' at 12b. Riding this inclined surface lbthe propeller arms 4 move on upwardly and at the same time swing in` a left-handed direction until the propeller finally'reaches the relative rotative position shownl-in Fig. 10, and the maiiiieo drelsV reach their relative rotative position,

also shown in that ligure and in Fig. 15.

And whenthe propeller'and fthe mandrels have thus frotated toward, the left to their full extent, thejpropeller arms-then occupy a position bearing against `the slotted wallI surface shown in Fig. 1 at 120,' and also shown `in dotted lines at 120V in Fig. l10, the propeller then being located just under Athe bearing' rib 12d against which the lower eylindric bearing end 42a ofthe cutter has a thi-'ust bearingwhen in its expanded posi- Y tion. The curved bearing face 12e ofthis bearing rib 12d is most clearly shown in Fig. 10.

Above the bearing rib 12d the slot 12 is shaped merely to provide space for the roller cutter 4-2; but near the upper end of the slot another bearing face 12,'F is provided and against which the upper cylindric bearing end 421) of roller 42 has a thrust bearing when in the position shown in Fig. 7. The position of this bearing face 12' is shown in Fig. 9 and is indicated in dotted lines in Fig. 7 and is also shown in Fig. 1. Above the bearing face 12]C the slot has a wall sur face 12g, shown in Figs. 1, 2, 3 and 8 against which the upper head 38 brings up when the parts are in their expanded positions. Likewise in the lower part of the slot there is a similar slotted wall surface 12h against which the lower head 3S brings up.

These various bearing surfaces, in the first place, limit the amount of left-handed rotation of the mandrels and in the second place take the thrust strain olf the mandrels when the rollers are expanded and are in operation. The direct thrust bearings of the rollers on the body at 12;" and 12e take the combined torsional and inward thrust which is imposed upon the cutters in opera tion and transmit that thrust directly to the body, without placing any large part of the thrust upon the mandrel and its bearings. However, whatever part of 'the thrust is placed upon the mandrel is, at the upper end of the mandrel, taken directly by the upper head 38 which has a direct thrust bearing on the body on surface 12g. And it will be noticed by reference to Figs. 3 and 8 that this surface 12g not only prevents further left-handed rotation of head 38 and thus takes directly all torsional strains imposed upon the head, but also it will be noticed that the surface 12g curves in behind the cylindric` inner end portion of the head so as to take also inward thrust. And at the lower end .of the cutter, any strain which is imposed upon the mandrel, from the cutter, tending to rotate the mandrel on around toward the left, is directly transmitted through the propeller arm 19,?) to the body surface 120 against which the propeller arm rests in the position of Fig. 7. Consequently, in the construction here eX- plained, substantially all heavy strains which would tend to bend the mandrel are taken off the mandrel and are transmitted directly from the cutter to the body.

Contraction of the cutters, their movement from the position of Fig. 7 to the position of Fig. 2, may be effected merely by pulling the tool up so that the cutters engage the lower end of the casing. Forcing the cutters down `relative to the body causes propeller 19 to move down, and the diagonal surface 12b causes the propeller to swing around to its position of Figs. 2 and 6. This enforced swinging of the propeller positively causes swinging of the mandrels from their expanded to their collapsed position, even though in their expanded positions they extend radially outwardly from the center of the tool and therefore could not be swunOv inwardly merely by straight inward pressure such as would be obtained from contact with the lower end of the casing.

In the form which has now been explained it will be observed that a single spring causes all of the expanding operations of the cutters. But in the form of Figs. 16 to 1S separate springs are provided for the several cutters, as will now be described. In general the body formation in these figures is the same as has been before described, the body slots 12 having the same configurations and the same bearing surfaces as before set forth. lere, however, the slot 12 at its lower end below the diagonal surface 12(7) has a somewhat elongated extension 12jl for the accommodation of the cutter lifting spring 121 which surrounds the lower eX- tended part 15a of the mandrel 15. The lower end of the mandrel, as before, has the head 38 and the bearing pin 36 of this lower end of the mandrel rotates in a bearing bore 37a in bearing collar 14a, as before described. But in this modification the bore is tapered so as to make place for a torsion spring 122, one end of which is set in a hole 123 in bearing collar 14a at the lower end of bore 37a, and the other end of which is set, as indicated at 124 in Fig. 17, in the end of bearing pin 36. The spring 122, of which there is one for each mandrel, tends to rotate the mandrel in a left-handed direction, while the individual springs 121, one for each mandrel and cutter, tends at all times to elevate the cutter. The general action of this modified form is the same as that hereinbefore described.

It remains only to describe the formation and interlocking arrangement of bearing block 14 and body 10, which is the same for both forms of the device, the only difference between bearing collar 14 and bearing collar lila being that the latter is thicker in order to accommodate the deeper bores 37a. This bearing collar is held between the lower end of the body and the sub 13 and has such interengagement with the body as to lock it against relative rotation. The bearing collar has upwardly projecting lugs 14o which extend up into the lower ends of the body slots, and it is in these upwardly projecting lugs that the bearing bores 37 or 37a are located. Also to strengthen the lower part of the body, the bearing collar is provided with a peripheral upwardly projecting flange 14o within which the lower end of the body fits, as best shown at 100 in Figs. 2 and 7. Thissurrounding of the lower end of the body bythe bearing collar Aflange strengthens the lower slotted end of the body very materially. Y

In the formof Figs. 1, etc; a water course ,to the drill bit 2d isprovided by a central bore 100 which is continuedfon down bv a `tube 101 that passes through propeller tube ter carrying member movable for expansion and contraction with -relation to the body, and a cutter mounted exclusively on said carrier and movable with relation thereto for expansion and contraction.

, 2. In an `expansive reamer, aY body, a cutter carrying member swingingly movable about an eccentric axis on the body, and a Vcutter mounted Von the carrier and movable` with relation theretolaterally of said axis. 3. In an expansive reamer, a body, acutter carrier movabletransversely of the body by 'swinging ,uponvalongitudinal axis, andl a cutter mounted on the carrier "and movable transversely relatively thereto;

4.@In an expansive reamer, a body having a longitudinalaxis, a cutter carrying member AmountedA on and movable with vrelation to the body in a direction transverse 'of the` .body axis, anda cutter mounted on said carrier andmovable with relation thereto in a direction transverse of the body axis.

5. In an expansive reamer, a body having a longitudinal axis, acutter carrier mounted on the body and movable with relation theretoin a direction transverse of the body axis. a cutter carried by the cutter carrier and movable longitudinally thereon, Aand. the car- -rierv and'cutter having interengaging formations causing transverse movement of `the cutter relative to theV carrier vby virtue of longitudinal.relativemovement v 6. In an expansive reamer, a body, a longitudinal cutter carryingmandrelmounted on the body to swing eccentrically about 4a longitudinal axis, and a cutter mounted on and surrounding the mandrel andmovable transversely with relation thereto.

7 In an expansive reamer, abody, a cutter carrying mandrel mounted on the body.`

to swing eccentrically about a longitudinal `axis,1and .a cutter mounted upon. and sur- .Arounding said mandrel and movable longitudinally with relation thereto, and thel cut-Y ter and mandrel having interengaging formations causing lateral movement of the cutter relativeto the mandrel by virtue of longitudinal movement of the cutter on the mandrel. Y i Y A `8 In an expansive reamer, a body, a eutcarrier 'and the' cutter engage when 1n exter carrier on the body, a cutter carried by said carrier and movable with relation tothe body between protracted and retracted positions, and vthe body havingV bearing `surfaces against 4which the cutter bears when in protracted position to transmit `applied thrust directly from the cutter to the body.

9. In an expansive reamer, a body,` a cutter carrier mounted on the body, a rotating cutter mounted on the carrier and movable with relation tothe body between protracted and retracted positions,'and a body and cutter having rotary bearing faces which are engagedV when the cutter is in protracted position to transmit applied thrust directly from the cutter to the body. A

10. In an expansive reamer, a body, a cutter carrier mounted on the body'for expanding and contractingV movement with relation thereto, a cutter mounted on said carrier for expanding and contracting movement 'with relation to the carrier, and bearing faces on the body with which the panded position.

11. In an expansive reamer, a body having Y aV longitudinal axis, a cutter carrying Inan- Y drel mounted on the body for swinging movement about a longitudinal axis between expanded and contracted positions, an

rotating roller cutter mounted on and surrounding the mandrel and movable transversely with'relationthereto for expansionand contraction, bearingfaces on thebod adapted to be engaged by the mandrel when in expanded position, and rotary bearing faces Aon the body adapted tobe engaged directly by the cutter when in expanded position..

l2, In an expansive reamer, a body with longitudinal slots therein, arranged symmetrically aboutV the central longitudinal axis of the body,a cutter carrying mandrel vin each body slot, said Amandrels being arranged to rotate eccentrically about the longitudinal axes which are eccentric of the body '-axis, whereby saidfmandrels may be swung to and from positionswithin the body slots and positions projected from the body slots,

Acutters mounted upon said mandrelsfori 'longitudinal movement with relation thereto, the cutters and mandrels having interengaging formations for causing transverse relative movement of the cutters by virtue of longitudinal relative movement thereof and spring actuated' means for swinging the .mandrels and forlmoving the cutters longi- 131.v In an expansive reamer, a body with longitudinal slots therein, arranged symmetrically about 'the central longitudinal axis of the body, a cutter carrying mandrel 'in each body slot` said mandrels being arranged torotate eccentrically about the longitudinal axes which are accenti-iwf the, body axis,

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whereby said mandrels may be swung to and from positions within the body slots and positions projected from the body slots, cutters mounted upon said mandrels for lonoitudinal movement with relation thereto, t ie cutters and mandrels having interengaging `formations for causing transverse relative movementJ of the cutters by virtue of longitudinal relative movement thereof, and spring actuated means for swinging the mandrels and for moving the cutters longitudinally, said spring actuated means comprising a cutter propeller movable along and rotatable about the central body axis and slidably engaging the mandrels, and a single spring for moving the propeller longitudinally and also rotating it about the body axis.

14. In an expansive reamer, a body with longitudinal slots therein, arranged symmetrically about the central longitudinal axis of the body, a cutter carrying mandrel in each body slot, said mandrels being arranged to rotate eccentrically about the longitudinal axes which are eccent ic oli' the body axis, whereby said mandrels may be swung to and from positions within the body slots and positions projected from the body slots. cutters mounted upon said mandrels for longitudinal movement with relation thereto, the cutters and mandrels having interengaging formations for causing transverse relative movement of the cutters by virtue of longitudinal relative movement thereof, and spring actuated means for swinging the mandrels and for moving the cutters longitudinally, the body slots having fearing faces against which the mandrels bear when in protracted position, and having also bearing faces against which the cutters bear when in protracted position.

15. In an expansive reamer, a body with longitudinal slots therein, arranged symmetrically about the central longitudinal axis of the body, a cutter carrying mandrel in each body slot, said mandrels being arranged to rotate eccentrically about the longitudinal axes which are eccentric of the body axis, whereby said mandrels may be swung to and from positions within the body slots and positions projected from the body slots. cutters mounted upon said mandrels for longitudinal movement with relation thereto, the cutters and mandrels having interengaging formationsfor causing transverse relative movement of the cutters by virtue of longitudinal relative movement thereof, and spring actuated means tor swinging the mandrels and for moving the cutters longitudinally, said spring actuated means comprising a cutter propeller movable 'along and rotatable about the central. body axis and slidably engaging the mandrels, and a single spring for moving the propeller longitudinally and also rotating it about the body axis, the body slots having bearing faces against which the mandrels bear when in protracted position, and having also bearing faces against which the cutters bear when in protracted position.

16. In an expansive reamer, a body with longitudinal slots therein, arranged symmetrically about the central longitudinal axis of the body, a cutter carrying mandrel cutters longitudinally, said spring actuated means comprising a cutter propeller movable along and rotatable about the central body axis and slidably engaging the mandrels, and a single spring for moving the propeller longitudinally and also rotating it about the body axis, the body slots having diagonally extending walls which cause rotation of the cutter propeller in one direction by virtue of longitudinal movement of the propeller in one direction.

17. In an expansive reamer, a body having a longitudinal central axis, a longitudinally extending cutter carrying mandrel mounted on the body to swing with relation thereto about an axis eccentric of the body axis, a cutter carried by the mandrel and movable longitudinally thereof, the cutter and mandrel having interengaging formations adapted to cause lateral movement of the cutter by virtue of its longitudinal movement on the mandrel, and a spring actuated means for causing swing movement of the mandrel and longitudinal movement of the cutter.

18. In an expansive reamer, a body having a longitudinal central axis, a longitudinally extending cutter carrying mandrel mounted on the body to swing with relation thereto about an axis eccentric of the body axis, a cutter carried by the mandrel and movable longitudinally thereof, the cutter and mandrel having interenwaging formations adapted to cause lateral movement of the cutter by virtue of its longitudinal movement on the mandrel, and a single spring actuated means for causing both swinging movement Vof the mandrel and longitudinal movement of the cutter.

19. In an expansive reamer, a body having a longitudinal central axis, a longitudinally extending cutter carrying .mandrel mounted on the body to swing with relation thereto about an axis eccentric of thebody axis, a cutter carried bythe mandrel and movable longitudinally thereof, the cutter and mandrel having interengaging formations adapted to cause lateral movement of the cutter by virtue of its longitudinal movement on the mandrel, a cutter propeller movable along and rotatable about the body axis and slidably engaging the mandrel in contact with a cutter, and a single spring for moving the cutter propeller longitudinally and for rotating it about the body axis.

20. In an expansive reamer, a body7 a cutter carrying member movable for expansion and contraction with relation to the body, and a cutter on said carrier and movable with relation thereto for expansion and contraction independently of the expansive and contractive movements of the carrier With relation to the body.

In Witness that I claim the foregoing I have hereunto subscribed my name this 13th day of December7 1927.

JOHN GRANT. 

